Research progress on pig low protein diet

Keywords In theory, the animal's need for amino acids can be provided by Purified diets. In this case, the animal does not need to provide the amino acids it needs by the protein in the diet, and the protein level of the diet can be zero. Mitchell (1968) pointed out that ideal proteins can be expressed as a mixture of amino acids or a protein that can be completely oxidized and metabolized, and this amino acid mixture should be identical in composition to the amino acid needs maintained and produced by the animal. Therefore, by adding synthetic amino acids and reducing the amount of protein raw materials to meet the animal's demand for amino acids (ie, maintaining the balance of amino acids), it is feasible in real production. Dietary formulas need to set amino acids rather than crude protein levels. This is the nutritional basis for reducing dietary crude protein levels and formulating low protein diets. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

In the past, due to the limited variety of amino acids produced in the industry, people can only guarantee the demand for amino acids through protein, resulting in excessive amino acid excess in traditional diets and high levels of feed crude protein, resulting in waste of resources and serious environmental pollution. As more and more industrial amino acids are available and prices are gradually reduced, it is a realistic possibility to use industrial amino acids, reduce the amount of protein materials to meet the amino acid requirements of animals, and reduce the crude protein content in feed. At present, the results and impact of low-protein diet research have exceeded the original goals. These studies have promoted people's deeper understanding of the metabolic needs of animals in theory, leaving an epoch-making imprint on the development of animal nutrition science. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

In the following, the results of the recent application of low-protein diets in pigs will explore the benefits that low-protein diets can create for feed companies and farmers. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

1 The effect of low protein diet on pig growth performance 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

A large number of previous studies have shown that under the condition of supplementing synthetic amino acids, when the dietary protein level is 2% lower than the recommended level of NRC (1998), there is no adverse effect on growth performance. However, if the dietary protein level is 4 percentage points lower than the recommended level by NRC (1988), the effects of lysine, threonine and tryptophan are also met, and the impact on pig performance is reported. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

Since 2004, as researchers have continued to experiment with the use of low-protein diets in pigs, the results have tended to be beneficial. Qiao Jianguo (2004) reduced the protein level of pig diets to about 12% and supplemented with lysine. The results showed that the use of low-protein plus lysine diets during the finishing period did not adversely affect pig daily gain, daily feed intake, and feed conversion ratio; and the use of low-protein supplemental lysine diets for pigs There were no significant effects on body weight, slaughter rate, backfat thickness and lean meat rate. Liu Xiaofan (2005) pointed out that the low-protein diet supplemented with balanced amino acids by adding synthetic amino acids based on the ideal protein model is of great significance in controlling livestock diseases and reducing environmental pollution, and low protein days. Grain increases the net energy concentration of the diet and is important for improving the energy level of low-energy diets. Wu Xin et al (2006) reduced the dietary levels of 20 and 50 kg pigs to 16% and 14%, respectively, and only added lysine. The results showed that the effects of low-protein diets on the growth performance, slaughter performance and pork quality of growing-finishing pigs were not significant; and there were slight optimization trends in the characteristics of backfat thickness and hydraulic performance. Hu Hongmei et al. (2007) reported that when the dietary lysine content was ≥0.9%, the protein was reduced by 2%, which did not affect the growth performance, slaughter performance and meat quality of the pig. Deng Dun et al. (2007) pointed out that the addition of lysine, methionine and threonine to low-protein diets can reduce the protein level of growing pigs from 18.2% to 14.5%, and significantly reduce nitrogen excretion. Affect its production performance. Tan Xin et al (2008) reported that the grain protein level was 4 percentage points lower than the recommended level of NRC (1998), while meeting the needs of lysine, methionine, tryptophan and threonine, the performance of pigs was not affected. Yin Huihong et al (2008) reduced protein levels by 4 percentage points in 20-50 kg of growing pig diets, and supplemented with appropriate essential amino acids, the net energy level was reduced to 9.45 MJ/kg, which did not affect pig growth performance. And apparent digestibility of nutrients. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

Since 2007, the author and his unit have reduced the protein level of pig diets by 4 percentage points in the NRC (1998) recommended standard on the subject of the impact of low protein diets on pig growth performance. It has no effect on pig growth performance and carcass quality, and is superior to high protein diet in growth trend and pig constitution, which is consistent with the results of the above studies. In addition, low protein diets can reduce diarrhea rates in piglets. Table 1 reflects the effect of crude protein levels in feed on the frequency of diarrhea in piglets. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

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2 The impact of low protein diets on the environment 5Ut China Feed Industry Information Network - based on feed, serving livestock

As the aquaculture industry becomes more and more serious, it is forcing more and more countries (including China) to limit the emission of pollution. In order to further expand the scale of production and avoid penalties caused by environmental problems, the aquaculture industry is more actively examining. Environmental problems caused by itself. These issues include nitrogen emissions, emissions of minerals such as phosphorus, and emissions of odors from the air. Among such pollution, nitrogen pollution and odor pollution are directly related to the crude protein content in the diet. Many studies have shown that low-protein diets can reduce nitrogen and phosphorus excretion in animals, supplement synthetic amino acids, reduce protein levels in pig diets, improve pig performance, improve feed conversion, and reduce nutrient emissions, especially nitrogen. The pressure on the environment from the pig industry. A pig consumes 8 to 9 kg of nitrogen from weaning to a weight of 100 kg. The nitrogen that is absorbed and deposited as lean meat does not exceed 3 kg, while 5 to 6 kg of nitrogen is excreted in the excreted nitrogen. Among them, 33% are in the stool and 67% in the urine. Table 2 shows the effect of a 1% reduction in dietary protein levels on pig nitrogen emissions. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

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3 The impact of low protein diet on economic benefits 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

With the development of animal husbandry, the lack of feed protein resources is becoming more and more serious. Saving the use of protein resources, reducing feed costs, and improving the economic benefits of pig production have become a hot topic in the feed and aquaculture industry. The recent increase in the price of soybean meal has made farmers more eager to reduce the amount of feed protein raw materials. In low-protein diets, the use of relatively expensive protein materials is reduced, and the use of inexpensive grain materials is increased. Therefore, low-protein diets are generally characterized by reduced feed costs. Many studies have reported that low protein diets reduce feed costs to varying degrees. Table 3 analyzes the cost of breeding low-protein diets and original high-protein diets. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

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4 Summary 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

In summary, the protein level of the diet is reduced by 4 percentage points compared with the NRC (1998) recommendation, and supplemented with lysine, methionine, threonine and tryptophan to meet the essential amino acid needs of pigs, and will not grow pigs. The performance has an impact; and it can significantly improve the efficiency of protein and energy utilization, greatly reduce nitrogen excretion (50%) and reduce the pollution of the environment of the excrement and urine, significantly improve the air quality of the pig house, and is conducive to the health and rapid growth of pigs. Significantly reduce feed costs, thereby creating higher economic benefits. However, whether the feeding of low-protein diets in fattening pigs leads to an increase in steroidal fat content is still controversial, but theoretically reducing the energy level of low-protein diets will be beneficial to improve carcass traits, and the actual effects in the later stages need to be further explored. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

Wu Shusong, College of Animal Science and Technology, Hunan Agricultural University, 410128, Changsha, Hunan. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry

Yang Qiang, National Feed Engineering Technology Research Center, China Agricultural University. 5Ut China Feed Industry Information Network - based on feed, serving animal husbandry